128164-94-3Relevant academic research and scientific papers
Heterocyclic β-Enamino Esters, 53. - Novel 5,8-Dihydropyrido- and 5H-Pyranopyrimidines
Wamhoff, Heinrich,Paasch, Joachim
, p. 995 - 999 (2007/10/02)
The 1,4-dihydropyridine enamino esters 1a and 4 react with phenyl isocyanate to afford the ureas 2 and 5, resp., which are cyclized to yield the 5,8-dihydropyridopyrimidines 3 and 6, resp., while the 1,4-dihydropyrimidine bisenamino ester 7a gives accordingly, via bisurea 8, the pyridodipyrimidine 10.The 2-amino-4H-pyran-3-carboxylate 11 is smoothly phosphorylated to form 12.Treatment of 12 with phenyl isocyanate results in a ring closure to the 4H-pyranopyrimidine 14.Similarly and according to this principle, the 5,8-dihydropyridopyrimidine 16 is smoothly formed upon treatment of the iminophosphorane 15 with phenyl isocyanate, while the 2,6-diamino-1,4-dihydropyridine 7b after phosphorylation affords the mono-iminophosphorane 17, which undergoes cyclization with isocyanate to the 5,8-dihydropyrimidine 18.With isopropylsulfamoyl chloride 1b and 7a form the mono- and bissulfamides 20 and 21, resp., which could not be cyclized further.
